gpio: stmpe: Improve a size determination in stmpe_gpio_probe()

Replace the specification of a data structure by a pointer dereference
as the parameter for the operator "sizeof" to make the corresponding size
determination a bit safer according to the Linux coding style convention.

This issue was detected by using the Coccinelle software.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-stmpe.c

@@ -437,7 +437,7 @@ static int stmpe_gpio_probe(struct platform_device *pdev)
 
 	irq = platform_get_irq(pdev, 0);
 
-	stmpe_gpio = kzalloc(sizeof(struct stmpe_gpio), GFP_KERNEL);
+	stmpe_gpio = kzalloc(sizeof(*stmpe_gpio), GFP_KERNEL);
 	if (!stmpe_gpio)
 		return -ENOMEM;